Associated-solution model

R.F. Brebrick, Ching-Hua Su, and Pok-Kai Liao, Associated Solution Model for Ga-In-Sb and Hg-Cd-Te... 

G. F. Neumark and K. Kosai, Deep Levels in Wide Band-Gap III-V Semiconductors D. C. Look, The Electrical and Photoelectronic Properties of Semi-Insulating GaAs R. F. Brebrick, Chmg-Hua Su, and Pok-Kai Liao, Associated Solution Model for Ga-In-Sb and Hg-Cd-Te... 

The partial structure factors for binary (Bhatia and Thorton, 1970) and multicomponent (Bhatia and Ratti, 1977) liquids have been expressed in terms of fluctuation correlation factors, which at zero wave number are related to the thermodynamic properties. An associated solution model in the limits of nearly complete association or nearly complete dissociation has been used to illustrate the composition dependence of the composition-fluctuation factor at zero wave number, Scc(0). For a binary liquid this is inversely proportional to the second derivative of the Gibbs energy of mixing with respect to atom fraction. 

In the development of the associated solution model used a number of general features have been obtained, which hopefully should prove useful. In particular it is shown in Appendix that the model behavior includes the occurrence of miscibility gaps in the liquid that do not require interaction coefficients that are large in magnitude and that are associated with an uncommon form for the Gibbs energy of mixing isotherms. 

The miscibility gap behavior contained in the associated solution model would appear to be complex and has only been touched upon here. Miscibility... 

It is therefore essential that thermodynamic modeling be applied to obtain a simultaneous quantitative fit to the phase diagram and thermodynamic data in order to evaluate the internal consistency of the various published data. Then a reliable framework can be established for smoothing, interpolating, and extrapolating experimental data that are costly and laborious to obtain. In Chapter 3 an associated solution model is presented. This model provides a good fit to the data for the Hg-Cd-Te system as well as for the Ga-In-Sb system, which is closer to the simpler picture of an ideal solution. 

A more accurate type of quasi-chemical solution model was introduced by Guggenheim [E. A. Guggenheim, Mixtures (Oxford University Press, New York, 1952)] to account for specific A + B AB association corrections in both Hfs (x) and st(x). The quasi-chemical approach employs an explicit pair partition function for the equilibrium population of A B complexes in solution. More general associated solution models were also developed to incorporate AB complexes of other than 1 1 stoichiometry [A. D. Pelton and M. Blander. Metall. Trans. 17B, 805-15 (1986)]. Although such quasichemical and solution models can be more accurate, they are also more difficult to implement. 

The most popular chemical theory postulates stoichiometric chemical species that interact accordingly as a regular solution (regular associated-solution model). The associated-solution model is based usually on the following assumptions ... 

Domain of Validity of the Ideal Associated Solution Model. 

As we can see, this quasi-chemical method is not dissimilar to the associated-solutions model discussed in seetion 2.5. This method has been rendered more generally applicable by writing what are known as quasi-equilibria - i.e. equilibria of the same t5q)e as above, but between... 

Was] Wasai, K., Mukai, K., Thermodynamic Analysis of Fe-Al-O Liquid Alloy Equilibrated with a-Al203(s) by an Associated Solution Model , J. Japan Inst. Metals, 52(11), 1088-1097... 

---